1. Field of the Invention
The invention pertains to the field of cutting inserts. More particularly, the invention pertains to a composite cutting insert having an intermediate portion disposed between a first portion and a second portion, the intermediate portion having a two-dimensional interlocking geometric shape for preventing movement of the first portion relative to the second portion and a plurality of openings to allow the first portion to bond directly to the second portion.
2. Description of Related Art
Cutting inserts employed for metal machining are commonly fabricated from composite materials due to their attractive combinations of mechanical properties such as strength, toughness, and wear resistance compared to other tool materials such as tool steels and ceramics. Conventional cutting inserts made from composite materials, such as cemented carbides, are based on a “monolithic” construction, i.e., they are fabricated from a single grade of cemented carbide. In this manner, conventional monolithic cutting tools have the same mechanical and chemical properties at all locations throughout the tool.
Cemented carbides materials comprise at least two phases: at least one hard ceramic component and a softer matrix of metallic binder. The hard ceramic component may be, for example, carbides of any carbide forming element, such as titanium, chromium, vanadium, zirconium, hafnium, molybdenum, tantalum, tungsten, and niobium. A common example is tungsten carbide. The binder may be a metal or metal alloy, typically cobalt, nickel, iron or alloys of these metals. The binder “cements” the ceramic component within a matrix interconnected in three dimensions. Cemented carbides may be fabricated by consolidating a powdered metal of at least one powdered ceramic component and at least one powdered binder.
The physical and chemical properties of cemented carbide materials depend in part on the individual components of the metallurgical powders used to produce the material. The properties of the cemented carbide materials are determined by, for example, the chemical composition of the ceramic component, the particle size of the ceramic component, the chemical composition of the binder, and the ratio of binder to ceramic component. By varying the components of the metallurgical powder, tools, such as inserts, including indexable inserts, drills and end mills can be produced with unique properties matched to specific applications.
In applications of machining today's modern metal materials, enriched grades of carbide materials are often desired to achieve the desired quality and productivity requirements. However, cutting inserts fabricated from a monolithic carbide construction using the higher grades of cemented carbides are expensive to fabricate, primarily due to the high material costs. In addition, it is difficult to optimize the composition of the conventional monolithic indexable cutting inserts comprising a single grade of carbide material to meet the different demands of each location in the insert.